Wavelength-selectable laser diode and optical communication apparatus including same

Abstract

Disclosed are a wavelength-selectable laser diode and an optical communication apparatus including the same. The wavelength-selectable laser diode includes a substrate, which includes a gain region, a tuning region spaced apart from the gain region, and a phase adjusting region between the tuning region and the gain region, a waveguide layer on the substrate, a clad layer on the waveguide layer, and gratings disposed on the substrate or the clad layer in the gain region and the tuning region.

What is claimed is: 
     
       1. A wavelength-selectable laser diode comprising:
 a substrate comprising a gain region, a tuning region separated from the gain region, and a phase adjusting region between the tuning region and the gain region; 
 a waveguide layer on the substrate; 
 a clad layer on the waveguide layer; and 
 gratings disposed on the substrate or the clad layer in the gain region and the tuning region, 
 wherein the gratings comprise: 
 a first grating disposed in the gain region and having a first grating length; and 
 a second grating disposed in the tuning region and having a second grating length different from the first grating length, 
 wherein the first grating includes first group gratings having first sampling lengths, 
 wherein each of the first group gratings includes first sub group gratings having first super structure grating lengths, 
 wherein each of the first sub group gratings includes first unit gratings having first pitches, 
 wherein the second grating includes second group gratings having second sampling lengths different from the first sampling lengths, 
 wherein each of the second group gratings includes second sub group gratings having second super structure grating lengths different from the first super structure grating lengths, and 
 wherein each of the second sub group gratings includes second unit gratings having second pitches different from the first pitches. 
 
     
     
       2. The wavelength-selectable laser diode of  claim 1 , wherein the first pitches include a 3rd pitch, a 4th pitch, and a 5th pitch, and
 the second pitches include a 6th pitch, a 7th pitch, and an 8th pitch. 
 
     
     
       3. The wavelength-selectable laser diode of  claim 2 , wherein the first super structure grating lengths include a 3rd super structure grating length, a 4th super structure grating length, and a 5th super structure grating length. 
     
     
       4. The wavelength-selectable laser diode of  claim 3 , wherein the second super structure grating lengths include a 6th super structure grating length, a 7th super structure grating length, and an 8th super structure grating length. 
     
     
       5. The wavelength-selectable laser diode of  claim 1 , wherein the first grating and the second grating comprise a sampled grating. 
     
     
       6. The wavelength-selectable laser diode of  claim 1 , wherein the first grating and the second grating comprise a super structure grating. 
     
     
       7. The wavelength-selectable laser diode of  claim 1 , wherein the waveguide layer comprises:
 a first active waveguide disposed in the gain region; and 
 a passive waveguide disposed in the phase adjusting region and the tuning region. 
 
     
     
       8. The wavelength-selectable laser diode of  claim 7 , wherein the substrate further comprises a modulating region adjacent to the tuning region,
 wherein the waveguide layer further comprises a second active waveguide disposed in the modulating region. 
 
     
     
       9. The wavelength-selectable laser diode of  claim 8 , wherein the substrate further comprises an amplifying region disposed adjacent to the modulating region,
 wherein the first active waveguide is disposed in the amplifying region. 
 
     
     
       10. The wavelength-selectable laser diode of  claim 8 , further comprising an electrode layer which is provided with electrodes disposed on the waveguide layer and pads connected to the electrodes and disposed on the clad layer outside the waveguide layer,
 wherein the electrodes comprise: 
 a plate electrode on the gain region; and 
 a heater electrode on the phase adjusting region and the tuning region. 
 
     
     
       11. The wavelength-selectable laser diode of  claim 10 , wherein the electrodes further comprise a cavity ring that surrounds one of the pads on the modulating region,
 wherein the cavity ring is disposed adjacent to the waveguide layer. 
 
     
     
       12. The wavelength-selectable laser diode of  claim 1 , further comprising:
 a lower electrode layer disposed below the substrate; and 
 a total reflection layer disposed on a side wall of the substrate adjacent to the gain region. 
 
     
     
       13. An optical communication apparatus comprising:
 a plurality of wavelength-selectable laser diodes; and 
 an optical combiner connected to the plurality of wavelength-selectable laser diodes, 
 wherein the each of the plurality of wavelength-selectable laser diodes comprises: 
 a substrate comprising a gain region, a tuning region spaced apart from the gain region, and a phase adjusting region between the tuning region and the gain region; 
 a waveguide layer on the substrate; 
 a clad layer on the waveguide layer; and 
 gratings disposed on the substrate or the clad layer in the gain region and the tuning region, 
 wherein the gratings comprise: 
 a first grating disposed in the gain region and having a first grating length; and 
 a second grating disposed in the tuning region and having a second grating length different from the first grating length, 
 wherein the first grating includes first group gratings having first sampling lengths, 
 wherein each of the first group gratings includes first sub group gratings having first super structure grating lengths, 
 wherein each of the first sub group gratings includes first unit gratings having first pitches, 
 wherein the second grating includes second group gratings having second sampling lengths different from the first sampling lengths, 
 wherein each of the second group gratings includes second sub group gratings having second super structure grating lengths different from the first super structure grating lengths, and 
 wherein each of the second sub group gratings includes second unit gratings having second pitches different from the first pitches. 
 
     
     
       14. The optical communication apparatus of  claim 13 , further comprising an optical amplifier connected to the optical combiner. 
     
     
       15. The optical communication apparatus of  claim 14 , further comprising optical waveguides which are connected to the waveguide layer and connect the plurality of wavelength-selectable laser diodes to the optical combiner. 
     
     
       16. The optical communication apparatus of  claim 13 , wherein one of the plurality of wavelength-selectable laser diodes is residual.